Get custom product attribute value inside product_attributes in WooCommerce

I need to confirm in a loop if the “visitor mail” (a custom product attribute) is what I get on the query string url loading.

My actual code is:

<?php if ( has_term( 'photos', 'product_cat' ) ) {
    
    if (isset($_GET['visitormail']) && count($_GET) == 1){ ?>
        
        <p class="photos-notify aligncenter">Visiting photos available for <strong><?php echo $_GET['visitormail']; ?></strong> &nbsp; &nbsp; [ <a href="/photos/">Change e-mail</a> ]</p>
    
        <?php
            woocommerce_product_loop_start();   
                                                          
            $args = array(
                //'meta_compare' => 'LIKE',
                'post_type'      => 'product',
                'meta_query' => array(
                    array(
                        'key' => '_product_attributes',                            
                        'value' => 'visitormail',
                        'compare' => 'LIKE'
                    )
                )

            );
            $loop = new WP_Query( $args );

            if ( $loop->have_posts() ) {
                while ( $loop->have_posts() ) : $loop->the_post();
                {
                    the_post();
                    /**
                     * Hook: woocommerce_shop_loop.
                     */
                    do_action( 'woocommerce_shop_loop' );
                    wc_get_template_part( 'content', 'product' );
                }
                endwhile;
            } 
    
            woocommerce_product_loop_end();
            ?>
        
    <?php }

In this way, I can “filter” those who only have “visitor mail” filled… but not the specific e-mail on the query string ($_GET[‘visitormail’]). I’ve already tried to insert “visitormail” as “key” but it doesn’t work!

Looks like I need to reach the 2nd “layer” of the product_attributes but I din’t found this.

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